It was a whale of a problem. Some species of the giant marine mammal had been hunted close to extinction 30 years ago. That was until a ban on commercial whaling in 1986 helped populations recover.

But the whale is not completely safe yet. Some countries, including Norway, refuse to acknowledge the ban. They continue to hunt whales for commercial reasons.

Other countries, like Japan, say they only hunt whales for scientific research. Earlier this year, the International Court of Justice (ICJ) ruled that Japan's whaling was not for scientific reasons, so it was banned.

Behind many of the campaigns to stop whaling is the US-based Sea Shepherd Conservation Society.

Since starting out in 1977, the group has taken a radical approach to stopping those who hunt whales illegally.

"Our strategy has always been hitting the poachers where it hurts the most - their profits," said Fiona McCuaig, a spokesperson for Sea Shepherd, while she was in Hong Kong last month.

"They are not listening to laws, government and public opinion. We want to put them out of business so [they] cannot afford to go [to hunt whales in places including Antarctica] anymore, because they are losing money."

Sea Shepherd employs some controversial methods to stop the whalers. The "marine guardians" have tracked down whalers on the seas, entangled their vessel's propellers with ropes, and thrown foul-smelling liquid onto the whales so they can't be sold for meat.

While some people hail the campaigners as heroes, those who don't welcome their extreme tactics call them sea pirates and eco-terrorists.

But McCuaig argues that confronting illegal whalers is the only way to protect whales when legal action fails. She added that Sea Shepherd is only enforcing conservation laws which are already in place.

For example, the group had long suspected that Japanese whalers were disguising commercial hunting as scientific research. Their suspicions were confirmed by the ICJ ruling in March. But between 1987 and 2013, 10,000 whales had already been killed by Japanese whalers.

McCuaig accepts that some people will disagree with the methods her organisation uses. But she defends the techniques, particularly the throwing of smelly liquid onto the whales. Others say the act is violent and endangers the lives of the whalers.

"Since the organisation [was set up] in 1977, no one has been seriously injured and that is the last thing we want to do," she said.

"We never aim bottles at someone's head. If we go down there with a banner saying 'please don't whale', the whalers are going to think we are a laughing stock. We have to have enforcement."

Despite the ICJ ban on Japanese whaling, Japan has hinted it will continue to catch whales for the sake of scientific research.

McCuaig acknowledges that while new bans are always encouraging, there is a long way to go before whaling is stopped completely.

"It was too good to believe that was the end of whaling," she said of the ban.

"But, look, whether [the Japanese] go down to Antarctica, or not, the judgment in the court case was a great argument for why [the Japanese] shouldn't be down there."

McCuaig said Sea Shepherd would stand their ground and continue to protect whales. In the meantime, the group is campaigning in the Faroe Islands to stop the tradition of hunting pilot whales and dolphins.

"If you have no hopes for saving whales - which is such a popular animal - you have no hope of saving other species," said McCuaig.